New Sweet Potato Publications

— Written By

Lina Quesada-Ocampo & Madison Stahr | Entomology & Plant Pathology

There are two new sweet potato factsheets available discussing the identification and management of Geotrichum Sour Rot and Southern Blight.

Southern blight, also known as sclerotial blight, southern stem rot, and bed rot is a foliar disease of sweet potato, affecting plants in greenhouse and field beds. Symptoms are usually observed around isolated circular hot spots which can spread over time, and appear after sprouts have emerged from the soil.

Symptoms manifest with a soft rot affecting the seed root, followed by the sudden wilt and subsequent death of a plant after sprouts have breached the soil line. In mild infections, symptoms may also be observed if plants are pulled from the bed, as infected slips will break off easily and have necrotic bases.

View the entire southern blight factsheet.

Geotrichum sour rot is caused by the ascomycete fungus Geotrichum candidum. As geotrichum sour rot is very reliant on favorable environmental conditions, the symptoms produced are highly varied, and thought to be dependent on the duration of favorable conditions. The most obvious symptom of an active infection is a wet, soft rot of the storage root combined with a distinct sour odor. During active infections, white mycelial tufts may also become present on the root surface. When favorable conditions are removed, affected areas on the storage root will exhibit a 1-3 mm collapse of the outer root tissue, which will become firm over time. These collapsed lesions will have highly irregular borders and can greatly vary in size and shape, but rot and decay of further tissue will cease. Geotrichum sour rot lesions can be associated with chilling injury wounds and the tips of shrink-wrapped roots.

Learn more about Geotrichum sour rot.